1. Industrial Field of the Invention
The present invention relates to a multichip mounted structure in which a plurality of integrated circuit (IC) chips are mounted on a substrate. In addition, the present invention relates to an electro-optical device in which an electro-optical material, such as liquid crystal, encapsulated between a pair of substrates is controlled so as to display characters, numerals, pictures, and the like. Furthermore, the present invention relates to an electronic apparatus composed of the electro-optical device.
2. Description of the Related Art
Currently, in electronic apparatuses such as mobile phones and mobile information terminals, liquid crystal devices using liquid crystal as an electro-optical material are widely used for electro-optical devices as display means. In many cases, the liquid crystal devices are used for displaying characters, numerals, pictures, and the like.
In the liquid crystal devices, in general, pixels are formed by crossing scanning electrodes formed on one substrate and data electrodes formed on the other substrate at a plurality of points in the form of a dot matrix. Light passing through liquid crystal in a pixel is modulated by selectively changing a voltage applied to the pixel, and thus, images, such as characters, are displayed. In addition to or instead of pixels in the form of a dot matrix, patterned electrodes for optional numerals, pictures, or the like may be formed on each substrate in some cases.
In these liquid crystal devices, in general, light passing through a selected pixel is modulated by applying a scanning voltage on the scanning electrodes by a liquid crystal driver IC and by applying a data voltage on the data electrodes, and thus, characters, numerals, or the like are displayed at the outside of one of the substrates.
There have been various known methods for connecting a liquid crystal driver IC, i.e., an IC chip, to a liquid crystal device. For example, a so-called COF (chip on FPC (flexible printed circuit)) method is known, in which IC chips are mounted on a relatively thin flexible printed circuit having flexibility, and then the printed circuit provided with the IC chips thereon is connected to a substrate which is an element for constructing a liquid crystal device. In addition, a so-called COG (chip on glass) method is known, in which IC chips are directly mounted on a substrate which constructs a liquid crystal device.
In liquid crystal devices and other devices using ICs, a plurality of IC chips are used when necessary, and in this case, a multichip mounted structure, i.e., a structure having a plurality of IC chips mounted on a substrate, is employed. In a conventional multichip mounted structure, a plurality of IC chips are disposed without having any positional relationship therebetween.
Various tools are used when IC chips are mounted on a substrate. For example, when IC chips are mounted on a substrate using a bonding agent, such as an ACF (anisotropic conductive film), the IC chips are heated and compressed on the substrate with the ACF or the like therebetween. That is, a compressive head is used as a tool for heating and compressing.
When the compressive head is used for manufacturing a multichip mounted structure, and when IC chips are disposed without having any positional relationship therebetween, as can be seen in a conventional multichip mounted structure, the compressive head must be moved in a complicated manner corresponding to locations at which the IC chips are disposed. As a result, there is a problem in that the configuration of the manufacturing apparatus having a compressive head is very complicated.
In addition, when IC chips are mounted using a bonding agent, such as the ACF, and when IC chips are disposed without having any positional relationship therebetween, the ACF or the like must be provided on a substrate so as to correspond to individual IC chips. Hence, there is a problem in that workability is very poor.
Taking the problems described above into consideration, an object of the present invention is that a plurality of IC chips are effectively mounted with high productivity and by a smaller number of manufacturing devices.
(1) To these ends, a multichip mounted structure of the present invention comprises a substrate provided with substrate-side terminals and a plurality of integrated circuit (IC) chips mounted on the substrate, each IC chip having IC-side terminals, in which the substrate-side terminals and the IC-side terminals are in conductive connection with each other, wherein the IC-side terminals formed on the plurality of IC chips form a pair of terminal lines opposing each other, and the plurality of IC chips are mounted on the substrate so that individual central lines between the pairs of terminal lines coincide with each other.
According to the configuration of the multichip mounted structure described above, the plurality of IC chips are mounted on the substrate so that individual central lines between the pairs of terminal lines of the plurality of IC chips approximately coincide with each other. Consequently, when a manufacturing tool, such as a compressive head, is disposed at a predetermined position, a material to be processed, such as a substrate, is linearly transported to the tool and a multichip mounted structure is manufactured by processing the material using the tool, the manufacturing tool is not required to be transported between the plurality of IC chips.
Next, as a method for mounting IC chips on a substrate, for example, methods of using a conductive bonding agent and a non-conductive bonding agent are known. As a conductive bonding agent, there are an ACF (anisotropic conductive film), an ACA (anisotropic conductive adhesive), an isotropic conductive paste, and the like.
The ACF is a conductive polymer film used for electrical and simultaneous connection between pairs of terminals provided with an anisotropic property. For example, the ACF is a film formed by dispersing a number of conductive particles in a thermoplastic or a thermosetting resinous film. By using the ACF, mechanical bonding between materials to be bonded together can be achieved by the resinous film, and electrical conduction between terminals of the materials to be bonded together can be achieved by the conductive particles.
The ACA is a conductive paste used for electrical and simultaneous connection between pairs of terminals provided with an anisotropic property. For example, the ACA is formed by dispersing a number of conductive particles in a bonding paste. By using the ACA, mechanical bonding between materials to be bonded together can be achieved by the paste, and electrical conduction between terminals of the materials to be bonded together can be achieved by the conductive particles.
As an isotropic conductive paste, there is, for example, a silver paste. When the isotropic conductive paste is used, electrical conduction between a plurality of pairs of terminals to be connected can be achieved by interposing the conductive paste between individual pairs of terminals.
As a non-conductive bonding agent, there are an epoxide bonding agent, an acrylic bonding agent, an urethane bonding agent, and the like. When the non-conductive bonding agent is used, mechanical bonding between materials to be bonded together can be achieved by the bonding agent, and electrical conduction between terminals of the materials to be bonded together can be achieved by direct contact between the terminals.
In the case in which one of various methods described above for conductive bonding or another optional method therefor is employed, when a plurality of IC chips are mounted without any positional relationship therebetween on a substrate as those in a conventional multichip mounted structure, bonding agents must be provided on the substrate corresponding to individual IC chips mounted thereon, and hence, workability is very poor.
In contrast, in the multichip mounted structure of the present invention as described above, when the IC chips are mounted on the substrate so that individual central lines between the pairs of terminal lines of the plurality of IC chips approximately coincide with each other, it is sufficient to simply provide a bonding agent, such as the ACF, linearly along the plurality of IC chips.
As a result, according to the multichip mounted structure of the present invention, a plurality of IC chips can be effectively mounted on a substrate with high productivity and by a smaller number of manufacturing devices.
(2) In the configuration of the multichip mounted structure as described above, at least one of the plurality of IC chips may be formed so that the external width of a surface provided with the pair of terminal lines differs from those of the other IC chips. This configuration can be formed, for example as shown in FIG. 1, using a plurality of IC chips 12a and IC chips 12b. 
(3)
In the configuration of the multichip mounted structure as described above, at least one of the plurality of IC chips may be formed so that the central line between the pair of terminal lines thereof deviates from the external central line of a surface provided with the pair of terminal lines. This configuration can be achieved, for example as shown in FIG. 9, in the case in which a plurality of IC chips 12c and 12b are mounted on a substrate 11, the external central line L0 of the IC chip 12c is not coincident with the central line L2 between the pair of terminal lines of the IC chip 12b, and the central line L1 between the pair of terminal lines of the IC chip 12c is approximately coincident with the central line L2 between the pair of terminal lines of the IC chip 12b. 
(4) In the configuration of the multichip mounted structure as described above, the substrate may be formed by a resinous material having flexibility. This configuration corresponds to a so-called COF (chip on FPC).
(5) In the configuration of the multichip mounted structure as described above, the substrate may be formed by a relatively rigid material having no flexibility, such as an epoxy substrate. This configuration corresponds to a so-called COB (chip on board).
(6) Next, an electro-optical device of the present invention comprises a pair of substrates opposing each other, an electro-optical material being encapsulated between the pair of substrates, and a multichip mounted structure in contact with at least one of the pair of substrates, in which the multichip structure is at least one of a multichip mounted structure according to one of the above (1) to (5).
According to the electro-optical device described above, a plurality of IC chips are mounted on the substrate so that individual center lines between the pairs of terminal lines of the plurality of IC chips approximately coincide with each other. Consequently, the first advantage is that a manufacturing tool is not required to be transported between the plurality of IC chips, when the manufacturing tool, such as a compressive head, is disposed at a predetermined position, a material to be processed, such as a liquid crystal panel, is linearly transported to the tool, and an electro-optical device is manufactured by processing the material using the tool. The second advantage is that a bonding agent, such as the ACF, for bonding IC chips is simply provided linearly along the plurality of IC chips.
As a result, according to the electro-optical device of the present invention, a plurality of IC chips can be effectively mounted on a substrate with high productivity and by a smaller number of manufacturing devices.
In the electro-optical device according to the above (6), liquid crystal may be used as the electro-optical material.
(8) Next, another electro-optical device of the present invention comprises a pair of substrates opposing each other, in which at least one of the pair of substrates is provided with substrate-side terminals, an electro-optical material being encapsulated between the pair of substrates, and a plurality of IC chips, each chip being provided with the IC-side terminals, in which the plurality of IC chips are mounted on at least one of the pair of substrates so that the substrate-side terminals and the IC-side terminals are in conductive connection with each other to form a multichip mounted structure, wherein the multichip mounted structure is at least a multichip mounted structure according to one of the above (1) to (3).
In the electro-optical device described in the above (6), the substrate constructing the electro-optical device and the substrate constructing the multichip mounted structure are different from each other. In contrast, in the electro-optical device described in the above (8), the substrate constructing the electro-optical device is the substrate constructing the multichip mounted structure. On this point, the electro-optical device described in the above (8) differs from that described in the above (6).
(9) In the electro-optical device described in the above (8), liquid crystal may also be used as the electro-optical material.
(10) Next, an electronic apparatus of the present invention comprises an electro-optical device and a housing containing the electro-optical device therein, in which the electro-optical device is composed of at least an electro-optical device according to one of the above (6) to (9). As the electronic apparatuses described above, there are, for example, mobile phones and mobile information terminals.